1. Field of the Invention
The present invention relates to a vehicular active noise/vibration/sound control system having at least two of an active noise control apparatus (hereinafter referred to as “ANC”) for reducing noise in a vehicle cabin based on a detected signal representative of engine vibrations, an active vibration control apparatus (hereinafter referred to as “AVC”) for reducing vehicle vibrations based on the above detected signal, and an active sound control apparatus (hereinafter referred to as “ASC”) for generating a sound effect in the vehicle cabin based on the above detected signal, and a vehicle incorporating such a vehicular active noise/vibration/sound control system.
2. Description of the Related Art
FIG. 8 of the accompanying drawings schematically shows an ANC-mounted vehicle 10N developed by the applicant of the present application. As shown in FIG. 8, the ANC-mounted vehicle 10N has an engine 12 whose ignition control is performed by an engine ECU 14 and which supplies engine rotation pulses Ep corresponding to explosion periods of the engine 12 through the engine ECU 14 to an ANC 16.
Noise that is primarily generated by explosions in the engine 12 is perceived by the ears of passengers seated on front and rear seats of the ANC-mounted vehicle 10N. Microphones 18, 20 are fixedly positioned on the interior roof or upper portion of seats near the ears of the passengers. Speakers 22, 24 fixedly mounted in the ANC-mounted vehicle 10N near the front and rear seats radiate canceling sounds for minimizing the sounds (noise) that are applied to the microphones 18, 20. The ANC 16 generates control signals S1, S2 that are supplied to the speakers 22, 24 to radiate the canceling sounds.
The ANC 16 comprises a reference signal generator 26 for generating a sine-wave reference signal proportional to the frequency of engine rotation cycles from the engine rotation pulses Ep and a pair of adaptive filters 28, 30 for changing the phase and amplitude of the reference signal to generate the control signals S1, S2 to minimize output signals from the microphones 18, 20.
FIG. 9 of the accompanying drawings schematically shows an AVC-mounted vehicle 10V developed by the applicant of the present application. Those parts of the AVC-mounted vehicle 10V which are identical to the ANC-mounted vehicle 10N shown in FIG. 8 are denoted by identical reference characters, and will not be described in detail below.
As shown in FIG. 9, the engine 12 is installed on a vehicle chassis by engine mounts 42, 44. The engine mounts 42, 44 incorporate respective actuators which are vibratable in synchronism with vibrations of the engine 12 to prevent the vibrations of the engine 12 from being transmitted to the vehicle chassis. The engine mounts 42, 44 are combined with respective load sensors 46, 48 doubling as vibration sensors. An AVC 50 generates control signals S3, S4 and supplies the control signals S3, S4 to the actuators of the engine mounts 42, 44 to cause the actuators to vibrate for thereby isolating the vibrations of the engine 12.
The load sensors 46, 48 supply their output signals to the AVC 50. The engine rotation pulses Ep are also supplied to the AVC 50.
The AVC 50 comprises the reference signal generator 26 for generating a sine-wave reference signal proportional to the frequency of engine rotation cycles from the engine rotation pulses Ep and a pair of adaptive filters 52, 54 for changing the phase and amplitude of the reference signal to generate the control signals S3, S4 to minimize changes in output signals from the load sensors 46, 48.
FIG. 10 of the accompanying drawings schematically shows an ASC-mounted vehicle 10S developed by the applicant of the present application. Those parts of the ASC-mounted vehicle 10S which are identical to the ANC-mounted vehicle 10N and AVC-mounted vehicle 10V shown in FIGS. 8 and 9 are denoted by identical reference characters, and will not be described in detail below.
The ASC-mounted vehicle 10S has an ASC 60 comprising the reference signal generator 26 for generating a sine-wave reference signal proportional to the frequency of engine rotation cycles from the engine rotation pulses Ep and a pair of acoustic controllers 56, 58 for changing the phase and amplitude of the reference signal to generate control signals S5, S6. The control signals S5, S6 are supplied to the speakers 22, 24 to cause the speakers 22, 24 to radiate a sound effect depending on the acceleration of the ASC-mounted vehicle 10S.
It may be proposed to install all the ANC 16, the AVC 50, and the ASC 60 in a vehicle to provide a more comfortable vehicle cabin environment.
There has been proposed a vehicular acoustic enhancement system including an ASC having a sound source for generating a sound effect and an ANC having an adaptive noise cancellation controller (see Japanese Patent No. 3261128). In the disclosed vehicular acoustic enhancement system, while the vehicle is being accelerated, the sound source outputs an accelerating sound simulating that of a high-output vehicle through a mixer and speakers, and the adaptive noise cancellation controller generates a noise cancellation signal based on a signal obtained from the engine and representing an engine rotational speed and a reference signal obtained from a microphone and supplies the noise cancellation signal to the mixer.
However, the vehicular acoustic enhancement system disclosed in Japanese Patent No. 3261128 is disadvantageous in that since the ASC and the ANC are activated at all times, they may interfere with each other depending on the running state of the vehicle, possibly impairing the noise and acoustic environment in the vehicle.
For example, when the ASC operates to emphasize the accelerating sound upon acceleration of the vehicle, the ANC operates to cancel the accelerating sound. As a result, the driver of the vehicle is unable to enjoy acceleration as is otherwise felt by the emphasized accelerating sound.